Electron tube



1936- c. w. HANSELL 2,066,037

ELECTRON TUBE Filed Sept. 15, 1954 lNVENTOR RH CLARE/V65 y/vsaz 7% WATTORN EY Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE ELECTRONTUBE Clarence W. Hanscll, Rocky Point, N. Y., assignor to RadioCorporation of America, a corporation of Delaware Application September13, 1934, Serial No. 743,813 Claims. (Cl. 250-275) 5 source toward ananode electrode and shifted inits passage between the source and theelectrode by means of some suitable deflecting field.

One of the primary objects of the present invention is that ofeliminating the effects of secondary emission from the anodes upon whichthe electron stream impinges.

A further object of the invention is that of lowering the internalresistance of the tube to the flow of electron currents.

Still a further object of the invention relates to general improvementsin the design of electron tube structure.

By the prior art, as is evidenced, for example, by my-previously issuedPatent No. 1,850,104, granted on March 22, 1932, assigned to RadioCorporation of America, I have shown an electron tube particularlyadapted for a system wherein the effects of tube noises are eliminatedand have applied a tube of the cathode ray type to use in an amplifyingsystem. By this arrangement of the prior art the efiects of secondaryemission from the anodes were reduced to some extent by providing ashield between the two anodes and the source of electrons. However, bythe present invention I have been able to overcome to a still greaterextent the detrimental effects of secondary emission in tube operationin a manner which was not heretofore attainable.

Briefly, the new feature embodied in the present invention consists inthe use of cup-like anodes so designed and spaced relative to theelements of the accelerating grid'that all of the electrons issuing fromthe emitting elementstriking the anodes do so inside the cup-shapedportion where there is very little, if any, potential gradient andwhere, as a result, secondary emission which results from electronimpact will not be drawn out.

The invention is illustrated'in one of its suggested forms by theaccompanying drawing, wherein:

Fig. 1- represents conventionally a sectional view through an electrontube of the type herein disclosed and shows the tube applied to anoperating circuit of the general type shown in my previouslyacknowledged patent; and

Fig. 2 illustrates a tube of the type shown in Fig. 1 also in sectionalong the line 2-2 of Fig. 1 looking in the direction of the arrows.

66 If reference is now made to the accompanying drawing, it will be seenthat I have provided a tube l formed of a glass envelope andappropriately evacuated. Within the tube l and supported from the stemportion 3, I have provided a large area cathode 5 which preferablyconsists of a thin piece of metal heated by low voltage low frequencyelectric current supplied thereto by means of conductors I and 9 at oneend and l and 9' at opposite end, so that two parallel supply paths areformed. The cathode of the preferred type as I have shown it preferablyhas a cross-section in a plane at right angles to its length whichapproximate very closely a parabola, since I have found that a largearea cathode ofparabolic shape will result in large electron emissioncombined with a concentration of the electron stream so that underproper conditions a closely concentrated beam of electrons ofconsiderable strength will be focused upon the center of theaccelerating grid structure I I.

The focusing of the electron stream issuing from the cathode may furtherbe improved by means of suitable control electrodes l3, for example,which are arranged substantially adjacent the emitting cathode and aregiven such shaping as to make them substantially continuations oftheparabolic shaping of the cathode. Of course, it is desirable in mostcases to provide some spacing between the controlling electrodes I3 andthe cathode structure 5 for insulating purposes. The electronbeam thusissuing from the cathode surface 5 and passing through the grid H andcontrolled by the controlling electrodes I3 is arranged to impinge uponthe internal portion of the cup-like anode members l5, I6 which aresupported within the end of the tube opposite the electron source.

As I have already pointed out in what has gone before, electrons issuingfrom the emitting surface 5 are drawn over to the anode members l5 andIt by virtue of the voltage applied between the anode and the emitterand upon striking the anode tend to cause the anode surface to emitsecondary electrons. By arranging the anode electrodes in cup-shapedfashion, as above explained, the effects of secondary emission do notextend beyond the boundary confines of the anode structure and,therefore, will not result in a current flowing from the anodes.

In order to provide further'improvements in the'operation of a tube ofthe general type herein disclosed, I have arranged at each end of theemitting electrode 5 a shield member I1, I!) for thelpurpos'e ofconcentrating the electron stream in a direction parallel to the lengthof the cathinputcircuitAtoa-n outputcirwit n. Aswas my above mentionedPatent No.

mm. Aoittlrding to the drawing, the shieldsireshownasconnectedtotheendsoithecathodeand forming, at the same time,apart of the cathode support.

Intheconstructionotatubeoithegeneral aratherlarge electron'emiasion.

'roprevent emission from one anode llor llrachingtheotheranodeandtoguardagalnst any possibility of inemciencies inoperation, shielding structure 2| is supported within the tube toseparate the two anodes, and in order to catch most oi the electronswhen no energy is applied on the control elements and also to catch allelectrons which are 'insufllciently de-" flected by the deflecting orcontrolling electrodes II to fall within the anode cups, the metal-likebrldgestructureflisprovidedinthegrld. Also, the grid structureinitsposition between the.

anodes II, II and the controlling electrode l3 electrodes".

Inordertoshowthegeneraltype'ofsystem adeviceqtthlstypeoperates,l'lg.ldrawing illustrates one suitable dorm enemistobe transmitted from one1,850,104, energy supplied from the input circuit is passed through thetransformer coupling I tuned y applied to the controlling electrodes l8connected to suitable terminals on the base member the tube IL Thecentral portion ofthe radio transmitter, for example, andthe outputissuitahlytunedbymeansoiacondens'er ll.

voltage for drawing the electrons from the emitting surface 3 toward theanodesili, ll

isprovidedbytheinolusionotsourcesot'potentialflandll.Betweentheemittera'ndthe anodmandgr'idsavoltegeotthesoumell aloneisappliedtothegridstructurell. Heatingcurrenttorheatingtheemitteriissuppiied by wayotasourcellandmaybeeitherdireetor alternating current;

Homiislgnalsareappliedin thelnputcircuit' A,they arecaused to aiiect orcontrol'thecontrolling ordeiiecting electroda llandthus'eausetheelectronstreamdevelopedtobepessedbe-- tween the two independentcup-like anode membei'siiand llwiththeresultthatcm'rentiiowsmeanso'ithecondenserflsoasto- "aoeaos': a e

inthewtputclreuit'BJs'wesexplainedinmy previouflymentionedpetent.

Whileithasnothereinbeenshowmitiaoi Having may described the invention.what no a plurality of cup-shapedanode memm I Irarrangedrelatlvetotheelectron unittir element, apair o! deflectingelemenh the emi tine el men the anodeaiia' calling the electron streamtobe shifted law-em the plurality of anodes,, andmeami'orshhldingtheanodesfromthedeflecting (An electron tube comprisingan-evacuated envelope, an elmaated electron emitting element orparabolic cross-section, a plurality 01' cupahaped anode memberssymmetrically arranged relative to the emitting element, and a pluralityor deflecting. elements positioned intermediate the emitflng element andthe anodes.'salddeflectingelecllolhalyingsubstantiallyintheplaneextendedol the surfaceof said emitting member. 5.Anelectron tubeeomprising anevacuatedenvelope, an elongated electron emitting element or paraboliccross-section, a plurality of cupsbapedanodenmnberssymmetricallyarrangedrelativetotheelnittingelement;apairotdeiiecting mi: intermediate theemitting elementandtheanodaanda shieldelementateachendotihecnittingelement for preventing ing at the unltted electrons init direction longi-..

tudimliy ot the unitting element.

a. An electron tube a an evacuated container homing therein an electrodeelement M to emit electrons, t pluol'anode adapted'to receive the ralityelectrons buing from the first electrode,anodeehnmtabdngcup-shapedtoreducesubatantiallytoaero the effectsoi'secondary electrunk-ma plurality of control electrodes positimedintermediatethe'electronsourceandtheanodemanberaandagridstruotureintermediate the control electrodes andthe anodes to provide feed back of energy from the anodes to the controlelectrodes.

'7. An electron tube comprising an evacuated envelope, an elongatedelectron emitting element of parabolic cross-section for emitting astream of electrons of substantial dimensions relative to the tubeenvelope size, a plurality of cupshaped anode members symmetricallyarranged relative to the electron emitting element, a pair ofdeflectingelements intermediate the emitting element and the anodeelectrodes for causing the electron stream to be shifted between saidplurality of anode electrodes, a shield element at each end of theemitting element for preventing spreading of the emitted electrons in adirection longitudinally of the emitting element, and means within theenvelope for shielding the anode electrodes from the deflecting elementsand electron source.

8. An electron tube comprising an evacuated container housing therein anelectrode element adapted to emit electrons, and an anode electrodeadapted to receive the electrons issuing from the emitting electrode,said anode element being constructed cup-shape so that electronsreceived thereby are unable to cause secondary electronic emission fromthe anode to have any substantial effect beyond the boundary limits ofthe anode structure.

9. An electron tube comprising an evacuated envelope, an electronemitting element within the envelope, a plurality of cup-shaped anodemembers symmetrically arranged relative to the emitting element, meansfor electrostatically shielding the anode members from each other, and apair of deflecting elements intermediate the emitting element and theanodes.

10. An electron tube comprising an evacuated envelope, an elongatedelectron emitting element of parabolic cross-section, a plurality ofcupshaped anode members symmetrically arranged relative to the emittingelement, means for electrostatically shielding the anode members fromeach other, and a pair of deflecting elements intermediate the emittingelement and theanodes.

11, An electron tube comprising an evacuated envelope, an electronemitting element within the envelope, a plurality of cup-shaped anodemembers symmetrically arranged relative to the electron emittingelement, means for electrostatically shielding the anode members fromeach other, a

pair of deflecting elements intermediate the emit-- ting element and theanodes for causing the electron stream to be shifted between theplurality of anodes, and means for shielding the anodes from thedeflecting elements.

12. An electron tube comprising an evacuated envelope, an elongatedelectron emitting element of parabolic cross-section, a plurality ofcup-shaped anode members symmetrically arrangedrelative to the emittingelement, means for electrostatically shielding the anode members fromeach other, and a plurality of deflecting elements positionedintermediate the emitting element and the anodes, said deflectingelectrodes lying substantially in the plane extended of the surface ofsaid emitting member.

13. Anelectron tube comprising an evacuated envelope, an elongatedelectron emitting element of parabolic cross-section, a plurality ofcup-shaped anode members symmetrically arranged relative to the emittingelement, means for electrostatically shielding the anode members fromeach other, a pair of deflecting elements intermediate the emittingelement and the anode, and a shield element at each end of the emittingelement for preventing spreading or the emitted electrons in a directionlongitudinally of the emitting element.

14. An electron tube comprising an evacuated container housing thereinan electrode element adapted when heated to emit electrons, a pluralityof anode members adapted to receive the electrons issuing from the firstelectrode, said anode elements being cup-shaped to reduce substantiallyto zero the effects of secondary electronic emission, means forelectrostatically shielding the anode members from each other, aplurality of control electrodes positioned intermediate the electronsource and the anode members, and a grid structure intermediate thecontrol electrodes and the anodes to provide feedback of energy from theanodes to the control electrodes.

15. An electron tube comprising an evacuated envelope, an elongatedelectron emitting element of parabolic cross-section for emitting astream of electrons of substantial dimensions relative to the tubeenvelope size,-a plurality of cupshaped anode members symmetricallyarranged relative to the electron emitting element, means forelectrostatically shielding the anode members from each other, a pair ofdeflecting elements intermediate the emitting element and the anodeelectrodes for causing the electron stream to be shifted between saidplurality of anode electrodes, a shield element at each end of theemitting element for preventing spreading of the emitted electrons in adirection longitudinally of the emitting element, and means within theenvelope for shielding the anode electrodes from the deflecting elementsand electron source.

CLARENCE W. HANSELL.

